Question

From a building , two balls A and B are thrown such that A is thrown upwards and B downwards (both vertically) If Vᴬ and Vᴮ are their respective velocities on reaching the ground , then [AIEEE 2002]
(a) Vᴮ > V ᴬ
(b) Vᴬ = V ᴮ
(c) V ᴬ> V ᴮ
(d) Their velocities depends on their masses ​

Answer 1

Answer:

If they are thrown vertically with same speed.

Thier final velocity will be same.

So,

B)Vᴬ = V ᴮ

Answer 2

Given:

• Two balls are thrown

1. upwards
2. vertically downwards

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Need to find:

• The relation between their respective final velocities

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Solution:

Let the ball A is thrown vertically upwards with speed u and ball B is thrown vertically downwards with the same speed u.

When A will come back to its point of protection after reaching the maximum height, it'll have the same velocity I.e. u at the point of protection.

If h be the height of the building,

then the velocity of A on reaching the ground is

From third equation of motion:

${v}^{2} - {u}^{2} = 2as \\ \implies \: {V}_{A}^{2} = {u}^{2} + 2gh$

 

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And that of B on reaching the ground is

is

From third equation of motion:

${v}^{2} - {u}^{2} = 2gh \\ \implies \: {V}_{B}^{2} = {u}^{2} + 2gh$

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 Thus $\large{\red{\bold{\boxed{{V}_{A}={V}_{B}}}}}$

》Option b is correct!